Wave signaling system



March 27, R523.

M. LATOUR WAVE SIGNALING SYSTEM Filed April 8. 1926 3 Sheets-Sheet 1 INVENTOR Nor/us la/our BY a ,OW M7 W.

ATTORNEY March 27, 1928. 1,663,712

M. LATOUR WAVE SIGNALING SYSTEM Filed April a. 1926 5 Sheets-Sheet 2 i lh l l' llllbh}? j 1 HNVENTOR Mar/us Z0 four ATTORNEY5 March 27, 1928. 1,663,712

M. LATOUR WAVE S IGNALING SYSTEM Filed April 8. 1926 3 Sheets-Sheet 3 & F "w l INVENTOR Mar/0.5 Lafour ATTORNEYS Patented Mar. 27, 1928.

UNITED STATES PATENT OFFICE.

HABIUB LATOUB, OF SAN SEBASTIAN, SPAIN, ASBIGNOB TO LA'I'OUR CORPORATION, OI

JERSEY CITY, NEW JERSEY, A CORPORATION OF DELAWARE.

WAVE BIGNALIN G BYS'IEI.

Application fled April 8, 1826. Serial ll'o. 100,549.

This invention relates to signaling sys tems and more particularly to amplifying devices for use in such systems.

In multi-stage am lifiers, especially those operating to amplify high rents, it has been recognized that the inherent capacities between the elements of the electron tubes of the amplifiers couple the circuits of such devices so that they operate as generators of high-frequency currents which tend to distort or mask the signal or signals to be amplified. Several methods have been proposed to overcome this difli culty, and the present invention has for its purpose a novel arrangement for neutrahzing the inherent capacity coupling between the output and input circuits of an electron tube amplifier in such a manner that the amplifier may function at high efficiency without distorting the amplified signal. Other features will appear from the description and appended claims, together with the drawings, in which- Fi 1 shows the invention applied to a multi-stage tuned radio-frequency receiver;

Fig. 2 shows a modified arrangement of the system of Fig. 1;

Fig. 3 shows a multi-stage tuned radiofrequency amplifier, having a common filament system provided with elements cooperating with the circuits of the amplifier to neutralize certain inherent capacity between the electrodes of the electron tubes thereof;

Fi 4 shows a radio receiver incorporatin t e present invention and having a plura ity of radio-frequency amplifying stages with the filaments of the electron discharge devices connected in multiple in a common heating system; i

Fig. 5 represents still another modification of the invention in the form of a radio receiver with the filaments of the electron tubes having a common series heating circuit in which certain elements are provided to cooperate with other means in the receiver to neutralize the capacity couplingbetween the input and output circuits of several electron to es.

Referrin especially to Fig. 1, there is represente an antenna system 6 in which -frequency curthere is included the primary windin of a step-u radio-frequency transformer the Secon ary winding 'of which shunted by a variable condenser 8, is included in the input circuit of the electron tube=9. 'The output circuit of this electron tube includes the primary winding 10 of a s -up radio-frequenc transformer 15, lategattery 11 and the fi ament circuitof-t e 'tube 9; The input circuit of the electron tube 13 includes the secondary winding 14 of the coupling transformer 15 and is tuned by the variable condenser 16. -The output circuit of the electron tube 13 is coupled to the input circuit of the detector 17 by means of a ste up radio-frequency transformer general y desi ated 18, and includes the primary win ing 19 of this transformer, plate bat-' tery 20 and the filament circuit ofthe tube 13. The input circuit of the detector in,- cludes the secondary winding '22 of the transformer 18 and a variable condenser 23, while the out ut circuit of the detector includes the in icating device 24, such as the telephones or loud speaker, and a plate battery 25. The detector just referred to is of the conventional type and need not be described further.

As indicated byfdotted lines and ca acities 26 and 27, the output circuit of eac fof the radio-fre uency amplifying stages is coupled to t e associated input circuit through an inherent ca acity notably that between the grid and p ate of the electron tube. In order to neutralize these last mentioned capacities, separate heatin batteries, such as 12 and 21, together wit separate plate batteries 11 and 20, are provided. It will be appreciated that there is capacity existing between these batteries which is diagrammatically represented at 28 in the dotted connection. In order to neutralize the capacity 26 of the tube 9, it is necessary to introduce ener into the input circuit of this device in suci a manner that there may be applied to its grid a potential equal and opposite to that which would normally be apfilied thereto through capacity 26. It wi be understood that an inherent capacity 31 exists efiectively between the filament system represented by oint 29 and the uppermost terminal of tile primar windin of the transformer 7 as indicate in dotte lines. The design and relation of the windings of the transformer 7 are such that the magnetic fields around the primary and secondary windings due to capacity current through capacity 31 is equal and opposite to that existing around said windings due to capacity current through capacity 26.

The couplingbetween the output circuit and the input circuit of the electron tube 13 is represented by the capacity 27. If a disturbing voltage in the plate circuit of the tube 13 is considered as existing across the points 32 and 60, this voltage causes a current to flow through the inherent capacity 27, the secondary windin r 14 of the transformer to the point 32. giinilarly, as a result of this disturbing voltage a current flows through the path including the inherent capacity 28, the primary winding 10 of transformer 15 to the point (30 on the plate circuit. The windings 10 and 14 are closely coupled and the capacity 28 is so chosen with relation to the number of turns of the primary winding 10 and the secondary winding 14 that the magnetomotive force of the winding 10 due to capacity current thru capacity 28 cancels that of the winding 14 due to the capacity current thru capacity 27, since it is assumed that the coils have the proper relative polarity to accomplish this result. By properly adjusting the spacing between the batteries 11, 12 and 20, 21, the inherent capacity 28 may be adjusted so that the undesired capacity coupling due to the inherent capacity 27 is neutralized, with the result that the amplifying device may have a high degree of amplification and still preserve the true character of the incoming signal. This result is obtained when the ratio of capacity 27 to ca acity 28 is substantially e ual to the ratio 0 the number of turns in winding 10 to the number of turns in winding 14.

Fig. 2 shows a receiver similar to the receiver of Fig. 1, but differs therefrom mainly by providing a common plate battery 34 for the radio-frequency amplifying electron tubes 35 and 36. A detector 37 operates in the well-known manner to rectify the incoming. signal and render it audible in the telephones or loud speaker, such as 38. It will be understood, of course, that a radiofrequency transformer 47 couples the antenna to the input circuit of the radio-froquency tube 35 and that the radio-frequency transformers 44 and 45 couple the circuits of the radio-frequency tubes 35 and 3G and of the detector 37, respectively. As in the arrangement of Fig. 1, inherent capacities such as 39 and 40 serve to couple the output circuits to the input circuits of the tubes 35 and 36, respectively. These conplings are undesirable, and it is necessary to neutralize them so that the amplifier may operate satisfactorily. In order to neutralize the inherent ca acity 39, the inherent capacity 46 effective y existing between the uppermost portion of the primary winding 47 and the filament circuit of the tube 35 is utilized after the manner of the arrangement of Fig. 1.

In the case of the inherent capacity 40, the inherent capacity 43 between the heating batteries 41 and 42 is utilized. If it is considered that a disturbing voltage in the plate circuit exists between the points 61 and (52, then a current flows in a circuit extending from point (32 through battery 3-1, inherent capacity 40, secondary winding of the transformer 44 to the point (El. Similarly, as a result of the disturbing voltage, a current flows in a circuit extending from the point 61, inherent capacity 43, through the primary winding of the transformer 44 to point (32. The capacity 43 is so arranged with respect to the number of turns in the primary winding and the number of turns in the sci-- ondary winding of transformer 44 taken with the inherent capacity 40, that the magnetomotive force due to capacity currentin said primary winding will cancel that of the secondary winding. No voltage due to capacity current will then be induced in either coil and, therefore, no variation will occur in the grid potential due to a variation in the plate potential; of course, assuming that the resistances of the coils are negligible in comparison with their roactances. Hence, the undesirable effect of the capacity coupling due to the inherent capacity 44) is eliminated.

In Fig. 3 there is shown an amplifier having the amplifying tubes 51 and 52 as in the preceding arrangements, in which inherent capacities 48 and 49 serve to couple the input and output circuits of the amplifier tubes 51 and 52 with the result that undesirable oscillations are produced. In order to neutralize the inherent capacity 48, the inherent capacity 63 effectively existing between the filament system and the upper portion of the primary winding of transformer 64 functions in the manner already described to neutralize the undesired coupling of the inherent capacity 48. In this arrangement, the filaments of amplifying tubes 51 and 52 are heated in parallel in a common heating circuit connected to a direct current source 50. Choke coils 56 and 57 in this common heating system are effective in reducing an alternating current component of the direct current source if such component is present. At any rate, the capacity 54 existing between the choke coils 56 and 57, as well as the connected circuits, is effective to neutralize the inherent capacity 49. It will be understood that if a disturbingvoltage exists across points and 66 of the plate circuit, a current will tend to flow in the path traceable from point 65, plate battery 67, inherent capacity 49 and the secondary winding of the transformer 68 to point 66. Similarly, this disturbing voltage will cause a current to flow in a path extending through point 65, the primary winding of transformer 68, the filament of tube 51 inherent capacity 54 to point 66. The value of the inherent capacity 54 and the number of primary turns of the transformer 68 may be so selected, the latter with respect to the number of turns in the secondary winding, that a neutralizing magnetomotive force in the primary winding will cancel that in the secondary winding. For this reason no voltage will be induced in either winding and there will result no variation in grid potential due to the disturbing voltage, under the conditions previously assumed.

In the arrangement of Fig. 4, two radiofrequency amplifying tubes 69 and 70, and a detector tube 71 are shown. The heating of the filaments of these tubes is also effected in a common heating circuit from a direct current source with the filaments connected in parallel, and differs from the arrangement I shown in Fig. 3 in that the heating current does not pass through the primary windings of the coupling transformers. In the arrangement under consideration, pairs of choke coils 73, 74 and 75 are placed in the parallel connections of the common heating circuit. These choke coils tend to reduce any alternating current component which may be present in the direct current source.

As in the foregoin arrangements, inherent capacity 72 existing between the input and output circuits ofthe amplifier 69 is neutralized by means including the inherent capacity 76. The inherent capacity 77 is neutralized by the inherent capacity 78 between the choke coils 7 3 and 74 when taken together with the primary winding of the transformer 79.

The radio receiver of Fig. 5 differs from that shown .in Fig. 4 mainly by havin a common series circuit for heating the laments of the amplifying tubes 80 and 81 and detector 82. Choke coils 83, 84, 85 and 86 are placed in the common heating circuit to prevent any disturbing effect from the alternatin component of the direct current source 8 As in the foregoing arran ements, the inherent capac ty 89 is neutra ized by the inherent capacity 90 and the primary winding of the transformer 91. Similarly, the inherent capacity 92 is neutralized by means of the inherent capacity 93 effectively existing between the elements in the heating circuit when taken together with the primary winding of the transformer 94. It should be pointed out that altho capacities 90 and 93 are indicated in the drawing as individual capacities existing between two definite points, this representation is actually that of the resultant of a number of capacities such as those existing between the wires and portions of the apparatus connected thereto. These resultant capacities are effective, for the purpose of this invention, between the points indicated in the various figures of the drawings and described in the specification as inherent capacities.

It will thus be seen that novel means are provided for neutralizing the capacity coupling existing between the input and output circuits of amplifying tubes which permits a high degree of amplification in an amplifier without the production of distortion or oscillations.

I claim:

1. An electric circuit arrangement for neutralizing capacity coupling between the input circuit and the output circuit of an electron tube due to capacity between the grid and plate electrodes, comprising a coil connected between one of these electrodes and the filament system, and a second coil and a neutralizing capacity effectivel connected in series between the other oi these electrodes and the filament system, said second coil being closely coupled with the first, said neutralizing c. pacity comprising solely an inherent capacity effectively existing between means in said filament system and auxiliary means associated with said circuits.

2. An electric circuit arrangement for neutralizing capacity couplin between the grid and plate circuits of an e ectron tube due to capacity between the grid and plate electrodes, comprising a coil connected between the grid and filament system, a second coil and a neutralizing capacity efi'ectively connected in series between the plate and filament system, said second coil being closely coupled electromagnetically to said first coi said neutralizing capacity comprising solely an inherent capacity effectively existing between means in the filament system and means associated with said circuits.

3. In a multi-stage amplifier including In each stage an electron tube connected to a filament system, the combination of a transformer coupling electron tubes in adJacent stages, one terminal of one winding of said transformer being connected to a grid electrode and a terminal of a second winding thereof being connected to a plate electrode of an adjacent electron tube, said terminals being of opposite polarity, and a capacity effectively connected in series between the other terminal of said second winding and the filament system, said capacity comprising solely an inherent capacity between means in the filament system and means associated with said circuits.

4. In a multi-stage amplifier, an electron llll tube provided with an input circuit and an to cause a current to flow to said input ciroutput circuit in each stage, means for new cuit which gives rise to a. potential equal tralizing capacity coupling between the inand opposite to that reduced by the current 10 put and output circuits of each stage, comflowing through sai capacity coupling.

I prising a capacity existing between certain In testimony whereof I aflix my signature.

elements in the filament heating system and a. coil connected in series with said capacity MARIUS LATOUR.

CERTIFICATE or CORRECTION.

,rmm No. 1,663,712. Granted March 27. 1928, to

MARIUS LATOUR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, after line I], insert the following as claims 5. 6 and 7,

5. An electron tube provided with an input circuit, an output circuit. and a filament heating system, means for neutralizing capacity coupling between said input and output circuits comprising a capacity existing between certain elements in the filament heating system and a coil connected in series with said capacity to cause current to flow to said input circuit which gives rise to a potential equal and opposite to that produced by the current flowing through said capacity coupling.

6. In an amplifier, an electron tube having an input circuit and an output circuit between which undesired capacity coupling exists, a common filament system, auxiliary equipment including a coil associated with said, circuits, and means in said filament'systcm between which a neutralizing capacity exists, said coil being closely coupled to one of said circuits and effectively connected in series with said capacity, whereby said capacity coupling is neutralized solely by said neutralizing capacity.

7. In a radio-frequency amplifier, a plurality of stages, each stage having an electron tube provided with an input circuit, an output circuit, and a filament system whereby undesired capacity coupling exists between the input circuit and the output circuit of each stage, a coil in the input circuit of each tube and an inherent neutralizing capacity effectively exist ing between respective portions of the filament systems of two successive tubes and effectively connected in series with a coil in the output circuit of the first of said two tubes, said coil being closely coupled with the coil in the input circuit of the second of said two tubes whereby said capscity coupling is neutralized solely by said inherent neutralizing capacity.;

and that the said Letters Patent should be read with this correction therein that thessme may conform to the record of the case in the Patent Office.

Signed and scaled this 1st day of May. A. D. 1928.

p M. 5. Moore, (Seal) Acting Gommissioner of Patents.

tube provided with an input circuit and an to cause a current to flow to said input ciroutput circuit in each stage, means for new cuit which gives rise to a. potential equal tralizing capacity coupling between the inand opposite to that reduced by the current 10 put and output circuits of each stage, comflowing through sai capacity coupling.

I prising a capacity existing between certain In testimony whereof I aflix my signature.

elements in the filament heating system and a. coil connected in series with said capacity MARIUS LATOUR.

CERTIFICATE or CORRECTION.

,rmm No. 1,663,712. Granted March 27. 1928, to

MARIUS LATOUR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, after line I], insert the following as claims 5. 6 and 7,

5. An electron tube provided with an input circuit, an output circuit. and a filament heating system, means for neutralizing capacity coupling between said input and output circuits comprising a capacity existing between certain elements in the filament heating system and a coil connected in series with said capacity to cause current to flow to said input circuit which gives rise to a potential equal and opposite to that produced by the current flowing through said capacity coupling.

6. In an amplifier, an electron tube having an input circuit and an output circuit between which undesired capacity coupling exists, a common filament system, auxiliary equipment including a coil associated with said, circuits, and means in said filament'systcm between which a neutralizing capacity exists, said coil being closely coupled to one of said circuits and effectively connected in series with said capacity, whereby said capacity coupling is neutralized solely by said neutralizing capacity.

7. In a radio-frequency amplifier, a plurality of stages, each stage having an electron tube provided with an input circuit, an output circuit, and a filament system whereby undesired capacity coupling exists between the input circuit and the output circuit of each stage, a coil in the input circuit of each tube and an inherent neutralizing capacity effectively exist ing between respective portions of the filament systems of two successive tubes and effectively connected in series with a coil in the output circuit of the first of said two tubes, said coil being closely coupled with the coil in the input circuit of the second of said two tubes whereby said capscity coupling is neutralized solely by said inherent neutralizing capacity.;

and that the said Letters Patent should be read with this correction therein that thessme may conform to the record of the case in the Patent Office.

Signed and scaled this 1st day of May. A. D. 1928.

p M. 5. Moore, (Seal) Acting Gommissioner of Patents. 

